A pharmaceutical company hopes to begin selling this year a fat-blocking pill directly to millions of overweight Americans who now only have access to a prescription version of the drug.

The Food and Drug Administration could approve over-the-counter sales of orlistat in the next few months, said George Quesnelle, president of GlaxoSmithKline Consumer Healthcare North America. If orlistat wins a nonprescription OK, it would become the first such weight-loss pill to win the FDA's sanction.

An FDA advisory panel voted 11-3 late Monday to recommend that the regulatory agency approve the nonprescription form of orlistat, which Glaxo would market as Alli (pronounced "ally"). The agency is not bound by the recommendation but usually follows the advice of its expert panels.

"We are excited about the potential opportunity to provide consumers with an FDA-approved over-the-counter option that promotes gradual yet meaningful weight loss," Quesnelle said.

When taken with meals, orlistat blocks the absorption of about one-quarter of any fat consumed. That fat — about 150 to 200 calories' worth — is passed out of the body in stools, which can be loose as a result. About half of patients in trials experienced gastrointestinal side effects, the company said.

Glaxo officials cautioned that orlistat is no magic pill: In six-month clinical trials, obese people who took the pills lost on average 5.3 pounds to 6.2 pounds more than did those who were given dummy pills. Once they ceased taking the drug, its effect stopped and they began to regain the weight they had lost, said Dr. Julie Golden, a medical officer in the FDA's division of metabolism and endocrinology products.

Quesnelle said people could resume use or seek help from a doctor if they gain weight.

"Orlistat is a tool that will help people control their calorie intake and modify their diet," said John Dent, the pharmaceutical company's senior vice president of research and development.

A bevy of potentially distasteful and embarrassing side effects struck about half the participants in trials of the drug. Those side effects, including fecal incontinence, gas and oily discharge that spotted the undergarments of trial participants, are likely to limit the appeal of the pill.

"Have you considered placing a warning on the box, 'Don't take this product while wearing your new La Perla underwear?'" panel chairman Dr. Alastair Wood, referring to the Italian brand of lingerie, asked company executives.

Discussion of the side effects recalled the hubbub that surrounded the FDA's approval in 1996 of the fat substitute Olestra, which also caused diarrhea and spotting. The agency initially required products containing Olestra to carry a warning label, making the fake fat the subject of jokes. In 2003, the FDA lifted the labeling requirement.

Glaxo wants people to use Alli for only six months at a time as part of an overall diet and exercise regimen.

The panel requested that the company conduct follow-up studies if and when the drug does reach the market, as well as rework the pill's label to ensure its proper use, Wood said.

"I think the drug is safe enough to be OTC. It's an OTC indication. Although there are some i's that need to be dotted and t's crossed, it's suitable for OTC use," Wood said following the vote.

Several panel members said they were concerned about the potential for abuse, especially by teens, as well as possible interactions with other drugs. Those drugs include cyclosporine, used by organ transplant patients, and warfarin, a blood thinner.

"In my mind there are some profound safety concerns regarding cyclosporine and warfarin and I think the labeling needs to be very explicit and very conspicuous to inform people about these possible safety hazards," said panel member and consumer representative Sonia Patten, an anthropologist at Macalester College in St. Paul, Minn.

Dr. Sidney Wolfe of the watchdog group Public Citizen urged the panel to reject the company's application, calling it a "desperate attempt to revive this barely effective drug by an OTC switch."

Taking the opposite view was Deborah Fisher, a nurse from the Baltimore area, who told the panel: "We need this new solution to losing weight and keeping it off."

"Eat less, move more: It sounds pretty simple, doesn't it? Well, as my kids say, not!" said Fisher, adding that she's dieted for 45 of her 52 years.

Glaxo licensed orlistat from Roche to develop the nonprescription version. Roche has sold Xenical, a prescription version of the drug, since the FDA approved it in 1999. Roche plans to continue selling Xenical regardless of the FDA's action.

Alli would contain half the dose of Xenical prescription capsules and would cost consumers $12 to $25 a week, Glaxo said. The company estimated 5 million to 6 million Americans a year would buy the drug if offered over the counter. Those numbers could mean at least $1.5 billion a year in retail sales.

British-owned GlaxoSmithKline's U.S. operations are based in Philadelphia and Research Triangle Park, N.C.